The present invention relates generally to machine milking of animals. More particularly the invention relates to a milking plant for milking animals according to the preamble of claim 1 and a cleaning method for a milking plant according to the preamble of claim 13. The invention also relates to a computer program according to claim 20 and a computer readable medium according to claim 21.
Automatic milking solutions are becoming increasingly efficient and sophisticated. Today, there is also a strong demand for flexible and animal-friendly milk production. For example, so-called milking robots have been introduced, which enable animals to autonomously decide when they are to be milked. In similarity with other types of milking plants, also these machines require cleaning to maintain a satisfying hygiene standard and to meet various regulatory requirements. Since, in contrast to traditional milking plants, the milking robots may be operated essentially at any time during the day, there are no natural specific occasions when it is appropriate to clean the milk line system of a milking robot. Moreover, taking the milking robot out of operation to manually clean its milk line system is a highly inefficient strategy. Instead, an entirely automatic cleaning procedure is desired. This approach is also advantageous from an animal-health point-of-view. Namely, one or more animals using the milking robot may undergo medical treatment, and therefore their milk cannot be mixed with the milk from the healthy animals. Based on the respective animal's identity, a computer system associated with the milking robot automatically directs any extracted milk that for various reasons is unusable (e.g. because it may contain antibiotics, or other undesired constituents) to a dedicated container. Additionally, subsequent to completion of extracting the unusable milk, the computer system orders cleaning of the milking robot's milk line system. In connection therewith the computer system must verify that relevant valves attain desired positions.
Furthermore, it is generally desirable that the milk line system is cleaned properly, the cleaning is completed rapidly without using excessive amounts of cleaning fluids. Today, pockets and drained pipe sections that are not included in the regular cleaning in place (CIP) procedure represent obstacles to accomplishing an efficient cleaning.
Therefore, a single boundary valve between the pipes of the milk line system under cleaning and the milk containing pipes is sought-after. At the same time, no cleaning liquids may enter into the milk, and thus contaminate the milk. However, a very limited leakage of milk into the system may be tolerated under cleaning. Naturally, any significant leakage in this direction will jeopardize the cleaning, or at least render the cleaning less efficient. Consequently, milk leakage into the cleaning fluid must be monitored.
To guarantee a satisfying operation, the milking plant and the valve means thereof are regularly subjected to maintenance and service. Naturally, for cost efficiency, it is desirable to avoid any unnecessary maintenance measures, and instead only repair any valves that actually require restoration.
U.S. Pat. No. 6,852,172 describes a solution for a milking plant wherein the milk line system from each milk collecting means can be shut off from the milk tank during cleaning of the milk line system. Potential leakage of detergent from the cleaning fluid to the milk in the milk tank is here prevented by providing a pressure difference between the two fluids, i.e. the milk and the cleaning fluid. Preferably, the pressure difference is achieved by connecting the cleaning fluid to the vacuum supply of the milking plant, while the milk side remains at atmospheric pressure. The tightness requirements on the shut-off valve can be relaxed, since although milk may leak into the milk line system, no cleaning fluid may leak into the milk tank.
Hence a prior-art solution is known, which is capable of separating cleaning fluid from milk. However, the problem of designing a milking plant, which on one hand allows failsafe and efficient cleaning of the milk line system while other parts of the milking plant contains milk; and on the other hand provides a quality indication for the valve means that separates the cleaning fluid from the milk during the cleaning process remains to be solved.